Piscine Erythrocytic Necrosis Virus in Atlantic Cod, Gadus morhua, and Other Fish: Ultrastructure and Distribution

Abstract

Electron microscopy of erythrocytes of Atlantic cod, Gadus morhua, with piscine erythrocytic necrosis (PEN) shows a small cytoplasmic viroplasm (~ 1 μm), often with an adjacent coherent group of large (330 nm) icosahedral virions. The viroplasm is Feulgen-positive, so the agent is an erythrocyte icosahedral cytoplasmic deoxyribovirus (EICDV) analogous to others reported in red cells of poikilotherms. PEN lesions in cod blood cells were found in 11–16% of samples from New Brunswick, Maine, and Georges Bank. PEN was found in cod of 15–80 cm total length taken at depths of 5–90 m. Incidence in the Georges Bank area was higher at depths of about 55 m. Intensity of infection varied from < 0.01 to ~ 99% of mature red cells, without obvious relation to cod size, sex, or condition, or to depth at which taken. PEN infections are reported in various other fish species and in other areas. Key words: viral infections, cytology, ultrastructure, morphology, pathology, Atlantic coast fishes